The third function of fan duct is to provide thrust augmentation
for the propulsion system.
The winning project, Distributed Propulsion System, presented an approach to aircraft thrust augmentation
intended to save billions in fuel costs across the Air Force.
Such a propulsion system called the inter-turbine burner (ITB), could enable power extraction, thrust augmentation
, reduced fuel burn, and specific thrust (ST) improvements.
Piper Aircraft is working with jet engine manufacturer Williams International to investigate a unique PiperJet thrust augmentation
system that could eliminate the need for its much-touted automatic horizontal stabilizer trim system to handle trim changes generated by the aircraft's single high-centreline FJ44-3AP turbofan engine.
The Jupiter-C did not use strap-on rockets; it had a set of rockets in the upper stage, but nothing that amounted to thrust augmentation
in the first stage.